This is a follow-up task of JDK-8280274. I think it still makes sense to only evaluate "CompilerPhaseTypeHelper::to_string(cpt)" when NOT_PRODUCT is defined, but we can do that in the function body. We should avoid from messing around interfaces with macros.

Actually, it's not necessary to have print_method_impl as a public interface at all. The only client of it is print_method().

Here is the current interface of Compile::print_method
V1: print_method(CompilerPhaseType cpt, int level)
V2: print_method(CompilerPhaseType cpt, Node* n, int level)

The only client of V2 is vector.cpp. It attempts to dump the phase name and vec_box node. It's impossible to to have n=NULL. No one will consume property <"phase :NULL">.

I think we should go in this way.
void Compile::print_method(CompilerPhaseType cpt, int level) {
  print_method(cpt, NULL, level);
}